SOIL EXHAUSTION AND ROTATION OF CROPS. 157 



been to take off a crop of rye once in three years, getting 

 about nine busliels,to the acre, leaving the soil to itself the 

 other two years. Three years of weathering, and atmospheric 

 action on that soil, put it into a condition to make a rye crop 

 of nine bushels to the acre.- If that rye were turned under, 

 instead of being cut off, so as to make the soil more retentive 

 of moisture, it could be brought up ; but the clover plant is 

 adapted to do that thing much more rapidly than the rye 

 plant. 



We now come to an important question, viz., the possibility 

 of continuing the same crop on a field indefinitely. Should 

 you ask me if that can be done, I could answer both " Yes " 

 and "No," and be equally right in each reply. There are 

 quite a number of agricultural questions that can be answered 

 in just that way. Instances can be brought up in which 

 almost any crop has been grown continuously, without inter- 

 ruption, or with no more interruption than the nature of the 

 plant requires, for a term of years — in many cases for a long 

 period of time. I mentioned yesterday the experience of Mr. 

 Lawes, who has groAvn wheat twenty-seven years in succession 

 on the same soil, and, without any manure has got an average 

 of 16 busliels to the acre ; while with manure he has averaged 

 36 bushels to the acre. "VVe kno"w that tobacco can be raised 

 year after year on the same soil, with the help of manure and 

 thorough tillage. The same is true of onions, buckwheat, rye, 

 in fact, I do not know of any crop that may not be grown in 

 that way. And yet, " circumstances alter cases." Clover 

 will not grow on this or that farm, or on this or that field, 

 with such and such culture, to advantage, unless an in- 

 terval is allowed between the crops. In some sections, you 

 cannot grow rye without interruption, and anybody can find 

 cases in which none of our crops will succeed, for several 

 years in succession, or even succeed at all. These differences 

 depend chiefly upon the soil, not upon the plant, and it is 

 dangerous to make any sweeping or absolutely general state- 

 ment where so variable a thing as the soil is concerned. 



Clover is a plant which has often given farmers a great 

 deal of trouble to grow year after year, or to cultivate in quick 



